A years-long ban on lawsuits will make federal and state laws on clean water standards and species protections harder to enforce, the groups said in the letter to Washington Sens. Patty Murray and Maria Cantwell and Oregon Sens. Jeff Merkley and Ron Wyden.

The groups urged the lawmakers to oppose the proposal “as written,” but said they generally support the idea of breaching the dams and helping impacted communities. The letter argues that the reason salmon aren't yet extinct on the Snake River is because of lawsuits to protect their habitat under environmental laws that were enacted after the dams were already built.